Although historians generally acknowledge that modern professional policing began with the creation of the London Metropolitan Police model in 1829, this book recognizes that law enforcement entities have been in existence since classical antiquity. Much of the book is devoted, however, to British policing and its antecedents in the British Isles, dating back to the sheriffs and constables of the 11th century. American policing dominates the entries due to its decentralized structure, which has led to the development of more than 20,000 police forces at the local, State, and Federal levels. It focuses on those American police forces that have been in the forefront of police professionalism, as well as those that have been marked by scandal or media scrutiny. This book also includes nontraditional examples of law enforcement, such as private detectives; vigilante groups; little-known Western lawmen; detective organizations; and forgotten members of Scotland Yard, the Surete, and the FBI. Several guidelines were used in preparing the more than 900 entries in this book. Biographical entries were selected with police experience in mind. An effort was made to include the people, events, and organizations that have not received the publicity of well-known law enforcement figures and agencies, but have nonetheless impacted law enforcement in various jurisdictions and countries. Sources for the information in each entry are indicated. 26 appendixes with supplementary information, a 183-item bibliography, and a subject index